This invention is related to the method of making heat-resistant polyester which has reduced amount of end carboxyl group (hereinafter this will be written as COOH).
Various methods have been proposed on the reduction of COOH of polyester. The typical example is known to be the method of reacting the polyester with epoxy compound. The present inventors examined this method and found that addition of the epoxy compound reduced the COOH but also caused a reduction in the degree of polymerization and that the epoxy compound has poor reactivity with the COOH of polyester, giving insufficient effect.